This invention relates to a system for the recording and/or playback signals, comprising a machine and tape-like record carriers which can be advanced in the system machine and by means of which continuous total-recording times of differing amounts can be obtained, this machine having, in order to indicate the continuous recording time corresponding to the particular amount of the record carrier advanced in the machine, a counter having an indicating element which travels along an indicating scale of predetermined total length and which can be driven from a drive device for the recording carrier via a speed change gear mechanism switchable in steps, which, in conformity with the continuous total-recording time of differing amounts, can be switched to different speed ratios inversely proportional to the corresponding continuous total-recording times, so that each of the continuous total-recording times of differing amounts can be indicated by means of the entire predetermined total length of the indicator scale.
Such a system is known from DE-AS No. 1,903,185. This known system comprises a so-called spool machine which is designed for receiving two spools and in which a recording carrier, during its advance is unwound from one spool and wound onto the other spool. The relevant spools of different sizes, onto which recording carriers of differing length are wound, can be inserted into the machine. Different advancing speeds can be selected for the recording carriers during recording and during playback, so that, depending on the spool size and the advancing speed, continuous total-recording times of differing amounts for information are obtained. To ensure that, of all the selectable continuous total-recording times of differing amounts, the continuous recording time corresponding to the particular length of recording carrier advanced in the system machine can be indicated by means of a counter having an indicating scale of fixed predetermined total length, the indicating element of the counter is driven via a speed change gear mechanism switchable in steps, the speed ratios of which are inversely proportional to the selectable continuous total-recording times. In the machine of the known system, the speed change gear mechanism has a crown gear wheel with three sets of teeth coaxial relative to one another and arranged in one plane on different diameters, and a pinion which is adjustable relative to the crown gear wheel in the radial direction of the latter and which can be engaged selectively with one of the sets of teeth of the crown gear wheel in order to switch the speed change gear mechanism. For this purpose, the pinion is attached to a shaft which is guided adjustably in the axial direction and which can be adjusted by means of a slide connected to it and shiftable via a manually adjustable actuating knob projecting from it. Thus, in this known system, the speed change gear mechanism for driving the indicating element of the counter has to be switched by hand. This makes it more complicated to operate the system and also entails the danger that the system user, when switching the speed change gear mechanism by hand, can make a mistake or forget manual switching completely, thus resulting in a misleading false reading.